1. Field of the Invention
The present invention relates to an inner deceleration type starter. In particular, the invention relates to an improvement in a starter having a planetary gear deceleration means.
2. Description of the Prior Art
FIG. 1 shows a conventional starter which includes a starter assembly 1, a D.C. motor 2 fitted to a bracket 3, and a ring gear 4 having a planetary gear mechanism fixed at the portion 3a of the bracket 3 in such a way as to be clasped together with an intermediate bracket 5 between the bracket 3 and the D.C. motor 2. The D.C. motor 2 also includes an armature 6. An output rotary shaft 7 of the D.C. motor 2 is supported by a sleeve bearing 8 which is fitted to an inner peripheral surface of the above-mentioned intermediate bracket 5, and a spur gear 9 which can be a sun gear, projects from the end of the rotary shaft 7. A planetary gear 10 is supported on a pin 12 which is, in turn, supported by a flange 13 via a bearing 11. The planetary gear 10 engages the ring gear 4 and the spur gear 9 so that the rotational speed of the spur gear 9 is decelerated and transmitted to the flange 13. An output rotary shaft 14 is fitted to the flange 13, and the front end portion of the output rotary shaft 14 is supported by sleeve bearing 16 which is located in a recess 15 which is formed in the inner peripheral end of the output rotary shaft. An overrunning clutch 17 has an outer clutch 18 which is helically spline-coupled to the output rotary shaft 14. A ring 19 is fitted into the outer clutch 18. A recessed groove B is formed between the ring 19 and a shoulder portion A of the outer clutch 18. A shift lever 20 is cam-engaged in the recessed groove B.
The conventional starter just described operates as follows. When the shift lever 20 is energized in such a way as to be moved, the overrunning clutch 17 is energized and moves forward so as to engage an engine (not shown). Then, an electric current is supplied to the armature 6 energizing the armature 6 which causes the rotary shaft 7 to rotate. The planetary gear 10 makes a planetary deceleration rotation within the ring gear 4 by the spur gear 9 which is provided at the forward end portion of the rotary shaft 7, so that the rotation power is transmitted to the flange 13 via the pin 12, thereby effecting the decelerated rotation of the output rotary shaft 14. As a result, the overrunning clutch 17 is energized and rotated via the outer clutch 18 which is spline-coupled to the output rotary shaft 14. Thus, an internal combustion engine (not shown) is started.
In the conventional starter, since the bearings 8 for supporting the rotary shaft 7, and the bearings 16 for supporting the output rotary shaft 14, are located along the longitudinal axial direction of the shafts 7, 14, and the groove B of the overrunning clutch 17 in which the shift lever is engaged is also displaced from these bearings along the longitudinal direction of the shafts 7, 14, the length in the longitudinal axial direction of the shafts 7, 14 is excessively long.